The present invention relates to Type I, Class B laboratory glasses as set forth in the standard specification in ASTM E 438-80a and particularly relates to barium-free soda-alumina-borosilicate laboratory glasses especially useful for pharmaceutical glass containers including ampuls, vials and syringes.
As set forth in ASTM E 438-80a (Standard Specification for Glasses in Laboratory Apparatus), Type I, Class B alumino-borosilicate laboratory glasses have the following chemical and physical requirements:
______________________________________ Weight Percent ______________________________________ Chemical Requirements Major Constituents, Approx. SiO.sub.2 73 B.sub.2 O.sub.3 10 Al.sub.2 O.sub.3 7 BaO 2 CaO 1 Na.sub.2 O 6 K.sub.2 O 1 Trace Constituents, Max. As.sub.2 O.sub.2 plus Sb.sub.2 O.sub.3 0.1 PbO 0.1 MgO 0.3 ZnO 0.1 All other con- stituents, max. 1.0 Physical Requirements Linear coefficient of expansion, 0 to 300.degree. C. cm/cm - .degree.C. .times. 10.sup.-7 48 to 56 .+-. 2 Annealing point, .degree.C. 574 .+-. 10 Softening point, .degree.C. 783 to 799 .+-. 10 Density, annealed, g/cm.sup.3 2.36 .+-. 0.02 Chemical durability, titration equivalent of: 0.02N H.sub.2 SO.sub.9 /10g of glass, max. ml 1.0 ______________________________________
It is desirable to have a laboratory glass for pharmaceutical containers made from a soda-alumina borosilicate glass composition that can be melted and fabricated into containers such as ampuls or vials with speed suitable for economical production. According to ASTM E 438-80a, a particular composition provides such a glass with an outstanding balance of chemical and physical properties including high chemical durability and a relatively low thermal coefficient of expansion.
However, during storage of the pharmaceutical containers, it is believed that barium from BaO in the glass may leach out very slowly in very small amounts and may react with minute quantities of sulfate or phosphate ions in the drug product to form precipitates which destroy the integrity of the product.
Hence, it is an object of the present invention to provide a barium-free glass composition that meets the relatively strict requirements of ASTM E 438-80a and that can be melted and fabricated economically by known tube drawing processes such as the Danner or downdraw processes.
It is an object of the present invention to provide a barium-free Type I, Class B laboratory glass according to the standard specification set forth in ASTM E 438-80a having a linear coefficient of expansion (0.degree. to 300.degree. C., cm/cm-.degree.C..times.10.sup.-7) of about 48 to 56 and having a chemical durability, maximum titration equivalent of: 0.02 N H.sub.2 SO.sub.4 /10 g of glass of 1.0 ml, the composition consisting essentially of the following ingredients in approximate percent by weight:
______________________________________ Ingredient Percent ______________________________________ SiO.sub.2 70-74 B.sub.2 O.sub.3 9-13 Al.sub.2 O.sub.3 5-8 Na.sub.2 O 5-8 K.sub.2 O 0-4 CaO 0-3 MgO 0-1 ______________________________________
the glass composition having an annealing point of about 550.degree. C. to 585.degree. C., a liquidus of about 1730.degree. F. to 1760.degree. F. and a Log n at the liquidus about 5.0 to 5.5.
It is an object of the present invention to provide a barium-free glass composition that meets the requirements of ASTM E 438-80a and yet can be economically processed into pharmaceutical containers, the composition having the following ingredients in approximate percent by weight:
______________________________________ Ingredient Percent ______________________________________ SiO.sub.2 71.8 B.sub.2 O.sub.3 11.5 Al.sub.2 O.sub.3 6.8 Na.sub.2 O 6.4 K.sub.2 O 2.7 CaO 0.5 MgO 0.2 ______________________________________
the glass composition having the following properties:
______________________________________ Property Approximate Units ______________________________________ Working Point (.degree.C.) 1135 Softening Point (.degree.C.) 782 Annealing Point (.degree.C.) 560 Strain Point (.degree.C.) 516 Expansion Coefficient (.times. 10.sup.-7) 54 Density (g/cc) 2.335 Chemical Durability (ml) 0.34 Viscosity, log 5 (.degree.F.) 1815 Viscosity, log 3 (.degree.F.) 2470 Liquidus (.degree.F.) 1740 Log n at Liquidus 5.4 ______________________________________
These and other objects are accomplished according to the specification that follows and the appended claims.